1. Field of the Invention
The present invention, in general relates to electrical cables and, more particularly, to a device for reducing friction.
On the tarmac at airports, heavy electrical cables that supply electrical power to aircraft must be dragged to and from the aircraft. These cables are long and heavy and friction intermediate an outer sheath of the cable and the tarmac makes this motion difficult to accomplish.
Therefore, an intermediate surface that is disposed between the cable and the surface upon which the cable is dragged that can reduce friction is desirable.
Two-piece prior art types of rings appear to be known for use with fluid transfer hoses (not cables) that are attached together by bolts. However, any ring that can separate, for example if the bolt loosens, can cause the ring to separate into two pieces and for the bolt and pieces to fall apart from the cable. It is not safe or permissible for debris to accumulate on the tarmac and in other areas as well.
Yet, there still is need of a way to attach a plurality of friction reducing electrical cable rings at spaced apart locations of an electrical cable. The rings ideally should not include separate component parts that can fall on the tarmac. There is also a preferred need to be able to attach these rings after an electrical cable has been assembled. It is not practical to do so before the cable is finished.
Furthermore, it is a requirement for the electrical cable to alternately be bent (i.e., curved to include a radius) and straightened during use. When any electrical cable is straight it maintains the same maximum outside diameter (OD) along its length. Any type of a ring that is placed around the electrical cable will, of necessity, extend for a portion along the longitudinal length of the cable. If the cable is straight, then the maximum OD that is experienced by the ring is the nominal OD of the cable.
However, when the electrical cable is bent the radius affects the effective OD of the cable. Because the inside of the ring experiences the OD of the cable along a portion of the cable's longitudinal length, whenever the cable is bent the OD experienced by the ring increases beyond the nominal OD of the cable itself. The inside of the ring experiences a substantial force urging it to expand as the electrical cable is bent.
Because a user is grasping the electrical cable and applying a force to bend it, as desired, a tremendous mechanical advantage occurs that magnifies the force applied to the cable proximate the ring. If the ring is in contact with the outside diameter of the electrical cable, the ring must accommodate this force that is urging it to expand. Accordingly, the ring can fracture or any method of securing it to the electrical cable will be compromised and fail prematurely as the electrical cable is periodically bent and straightened.
Also, several electrical cables are simultaneously required for certain applications. At present according to known prior art methods, a plurality of individually jacketed cables are disposed in a generally parallel longitudinal orientation with respect to each other and are secured in this general position by the use of either a plurality of steel bands, tape, or by a coating of shrink tubing of combination thereof. These methods of securing the individual cables together in a bundle add to the cost of manufacture and increases the weight of the total cable assembly, which makes movement of it all the more difficult.
Accordingly, there exists today a need for a friction reducing electrical cable ring for use with an electrical cable that helps ameliorate the above-mentioned difficulties.
Clearly, such an apparatus would be a useful and desirable device.
2. Description of Prior Art
Rings for hoses are, in general, known. Part No. DB4042/DBA11502 by Fluid Transfer with information available on the web at “fluid-transfer.co.uk” is sold specifically for fluid transfer applications and it secures two halves together around a hose by a brass set screw. While the structural arrangements of the above described device may, at first appearance, have similarities with the present invention, it differs in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.